Differential pressure relief valve

ABSTRACT

A differential pressure relief valve wherein a diaphragm piercing device is actuated by differential pressure through a bellows. The device is self-contained and is installed in the bulkhead of a sealed container. As the pressure inside the container becomes greater than the pressure outside, the bellows compresses to a fixed compressed height of the bellows, and a spring loaded hollow plunger is released and is driven through a diaphragm on the bellows end, thus venting the container to the outside atmosphere. In one embodiment the bellows and spring biased plunger are interlocked so that the diaphragm is moved against the combined resistance of the bellows and spring. In another embodiment the bellows is compressed independently of the spring.

represented by the Secretary of the Navy, Washington, DC.

United States Patent 11 1 1 1 3,742,968 Kennedy July 3, 1973DIFFERENTIAL PRESSURE RELIEF VALVE Primary Examiner-Henry T. KlinksiekAssistant Examiner-'-Richard Gerard [75] Inventor' Robert Kennedy SanJose Cahf' Attorney-R. S. Sciascia and Charles D. B. Curry [73]Assignee: The United States of America as 5 7] ABSTRACT [22] Filed: Mar.22, 1971 A differential pressure relief valve wherein a diaphragmpiercing device is actuated by differential pres- [211 Appl' 126752 surethrough a bellows. The device is self-contained and is installed in thebulkhead of a sealed container. [52] US. Cl. 137/68, 220/89 A As thepressure inside the container becomes greater [51] Int. Cl. Fl6k 17/40,B65d 51/16 han the pressure utside, the b llows compresses to a [58]Field of Search 220/89 A; 137/68, fixed compressed height of thebellows, and a spring 137/69, 71 loaded hollow plunger is released andis driven through a diaphragm on the bellows end, thus venting the con-[56] References Cited tainer to the outside atmosphere.

, UNITED STATES PATENTS In one embodiment the bellows and spring biased1,117,639 11/1914 Cooey 220/89 A x Plunger are interlocked 80 that thediaphragm is moved 1,704,944 3 1929 Johann '-137 3 x against thecombined resistance of the bellows and 1,951,897 3/1934 Binckley.....137/68 X spring. In another embodiment the bellows is 2,304,417 l2/l942Mason 220/89 A compressed independently of the spring.

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INVENTOR ROBERT F. KENNEDY ATTORN Y DIFFERENTIAL PRESSURE RELIEF VALVEThe invention described herein may be manufactured and used by or forThe Government of the United States of America for governmental purposeswithout the payment of any royalities thereon or therefor.

The present invention relates generally to a differential pressurerelief means to force pierce a metal diaphragm when the internalpressure of a receptacle in which the valve is mounted reaches apredetermined degree, and more particularly, to a device in which ametal diaphragm is mounted in a bellows and moves with the bellows asthe bellows is compressed by the differential pressure. In conventionalruptured diaphragm devices the diaphragms and bellows operateindependent of each other, which can cause a lag or delay in actuatingand piercing the diaphragm. The present invention will overcome theaforementioned problem of actuating pressure reliefvalves. Moreover, thepresent invention provides a much simpler as well as a more reliablemeans for actuating diaphragm pressure relief devices.

The major object of the invention is to provide a spring loaded pressurerelief device to force pierce a metal diaphragm.

Another object of the invention is to provide a spring loaded pressurerelief device that is adjustable to actuate at narrow lateraldifferential pressure ranges.

Another object of the invention is to provide a differential pressurerelief valve that is reliable in narrow differential pressure ranges.The following is a description of the invention and from theaccompanying drawings of the preferred embodiment of the presentinvention wherein other objects and features will be aparent:

FIG. 1A is a sectional, sequential operational view of the devicewherein the bellows and spring biased plunger are interlocked and in thepre-actuated condition;

FIG. 1B is a sectional, sequential operational view of the device in theactuated condition;

FIG. 1C is a sectional, sequential operational view of the device in theactuated condition;

FIG. 2A is a sectional, sequential operational view of the devicewherein the bellows are compressed independently of the spring and inthe pre-activated condition;

FIG. 2B is a sectional, sequential operational view of 33, internal airinlet ports '35, external air outletports 37. Plunger retaining balls 27project into the recessed portion 23a of plunger 23 to retain plunger 23in a fixed or preactuation position.

Referring to FIGS. 1A, 1B, and 1C wherein diaphragm 33 of pressurerelief valve 13 is pierced by 4- blade cutter 25 mounted onspring'biased plunger 23 when the internal pressure of receptacle 11 inwhich valve 13 is mounted reaches a predetermined pressure. 1

Receptacle 11 may be any sealed container requiring a differentialpressure monitoring system and is not considered as part of theinvention.

Casing 15 is divided into two compartments comprising a bellows cavity17 and a central bore 19. The lower portion of central bore 19 isthreaded to accept nut 31. Assembled in bellows cavity 17 is circularbellows 21. The upper portion of circular bore 19 is superimposed bydiaphragm 33 which overlaps onto the top portion of circular bellows 21and bellows cavity 17.

Referring to FIG. 13 wherein two-part casing 15 has air inlet ports 35which allows the internal pressure of receptacle 11 to communicate thecircular bellows 21 and diaphragm 33. Plunger 23 is mounted in centralbore 19 so that 4-blade cutter or piercing element 25 is mounted at oneend of plunger 23, while the opposite end of plunger 23 is attached tocoil biasing spring 29 which is in turn attached to hollow adjustablenut 31 located in the external air outlet 37 of central bore 19. Theinterior wall of external air outlet 37 is threaded to accept adjustablethreaded nut 31. The effective pressure of spring 29 can be adjusted byadjustable threaded nut 31 by turning nut 31 into the threaded portionof air outlet 37 of central bore 19. The spring pressure is counteractedby the biased retaining balls 27 to prevent inadvertant actuation ofplunger when the biasing spring 29 and plunger 23 are activated bymovement of bellows 21. The summation of the bellows spring force andthe plunger spring force determine the actuating force. The plungerspring force can be adjusted by adjustable nut 25, making it possible tovary the actuating force, thus allowing relaxation of the spring ratetolerance and still maintain capability to obtain the desired actuatingforce.

Referring to FIG. 1A, diaphragm piercing device or 4-blade cutter 25 isactuated and controlled by circular bellows 21. In the inoperativecondition the external pressure (P,) is greater than the internalpressure (P,). Referring to FIG. 18, when the internal pressure (P,)exceeds the external pressure (P,,), plus the bellows force, plunger 23is free to move, thereby activating 4- blade cutter piercing device 25.Referring to FIG. 18, at a preset compressed height of the bellows 21,the spring loaded plunger 23 is driven down in central bore 19 untilplunger retaining balls 27 are free to move into recess 19a therebyreleasing spring loaded plunger 23 to be driven upward by biasing spring29, causing 4- blade piercing device 25 to pierce diaphragm 33 onbellows 21, thus venting receptacle 11 to the outside atmosphere. In theactuated condition, as illustrated in FIG. 1C, the internal pressure(1%) equals the external pressure (P,) because plunger 23 is driventhrough diaphragm 33 thereby interconnecting the internal and externalpressure sources.

Alternative Embodiment. Referring to FIGS. 2A, 2B, and 2C in thealternative embodiment, circular bellows 21 is compressed independentlyof plunger spring 29. Plunger spring 29 is preset to any desired force,but is not compressed with or actuated by the movement of bellows 21.Thus the plunger driving force is infinitely variable'and actuatingforce is controlled entirely by the compression of spring 29.

Referring to FIG. 2A, when the external pressure (P,,) is greater thanthe internal pressure (1 plunger 33 is retained in place or locked byplunger retaining balls 27. 7

Referring to FIG. 28, when the internal pressure (P,) is greater thanthe external pressure (P,), plus the bellows force, plunger 23 will movedownward and recess will become adjacent balls 27, thereby freeingplunger 23 to be driven upwards and activating 4-blade piercing device25.

Referring to FIG. 2C, when 4-blade cutter 25 pierces diaphragm 33, thediaphragm is severed, thereby venting receptacle 11 to the outsideatmosphere. In the actuated condition the internal pressure (P is equalto the external pressure (P What is claimed is:

l. A differential pressure relief valve for a receptacle having anexternal ambient air pressure greater than the internal air pressurecomprising in combination:

a. a vented casing body positioned in said receptacle, said ventedcasing body providing an air path to the ambient external air;

b. a compressing means positioned in said vented casing body andresponsive to a differential of said ambient-internal pressure formovement within said body;

c. a rupturable diaphragm positioned in said vented casing body andlocated within and operatively coupled to said compressing means formovement therewith; said diaphragm closing said air path;

d. a diaphragm piercing means positioned in said vented casing body andincluding means biasing said piercing means towards said diaphragm; and

e. retaining means holding said piercing means in a retracted positionand responsive to movement of said compressing means upon apredetermined pressure differential being present to rlease saidpiercing means for rupturing said diaphragm.

2. The device recited in claim 1 wherein said vented casing bodycomprises a first chamber, second chamber, and ventng ports wherein saidcompressing means is positioned in said first chamber and said piercingmean is positioned in said second chamber, said diaphragm beingoperatively positioned within said compressing means whereby saiddiaphragm moves while said compressing means compresses.

3. The device recited in claim 2 wherein said compressing means isoperatively connected to said piercing means whereby movement of saiddiaphragm is resisted by the combined actuating force at saidcompressing means and said piercing means.

4. The device recited in claim 3 wherein said compressing means is abellows and is operatively connected to said piercing means.

5. The device recited in claim 4 wherein said piercing means comprises acutter and a biased plunger located interjacent said bellows.

6. The device recited in claim 5 wherein said piercing means includes anadjusting means which is vented to ambient air pressure.

7. The device recited in claim 2 wherein said venting ports comprise aninternal venting port and an external venting port wherein said interalport is in communication with said first chamber whereby the internalair pressure impinges on said compressing means and said diaphragm, saidexternal port opening onto said piercing means and said diaphragm and incommunication with ambient air pressure.

8. The device recited in claim 7 wherein said compressing means isoperatively connected to said piercing means whereby said internal airpressure equals said ambient air pressure after said piercing meanspierces said diaphragm.

9. The device recited in claim 8 wherein said compressing means iscompressed independently of said piercing means.

10. The device recitedin claim 9 wherein said compressing means is abellows and said piercing means comprises a 4-blade cutter.

1. A differential pressure relief valve for a receptacle having anexternal ambient air pressure greater than the internal air pressurecomprising in combination: a. a vented casing body positioned in saidreceptacle, said vented casing body providing an air path to the ambientexternal air; b. a compressing means positioned in said vented casingbody and responsive to a differential of said ambient-internal pressurefor movement within said body; c. a rupturable diaphragm positioned insaid vented casing body and located within and operatively coupled tosaid compressing means for movement therewith; said diaphragm closingsaid air path; d. a diaphragm piercing means positioned in said ventedcasing body and including means biasing said piercing means towards saiddiaphragm; and e. retaining means holding said piercing means in aretracted position and responsive to movement of said compressing meansupon a predetermined pressure differential being present to rlease saidpiercing means for rupturing said diaphragm.
 2. The device recited inclaim 1 wherein said vented casing body comprises a first chamber,second chamber, and ventng ports wherein said compressing means ispositioned in said first chamber and said piercing means is positionedin said second chamber, said diaphragm being operatively positionedwithin said compressing means whereby said diaphragm moves while saidcompressing means compresses.
 3. The device recited in claim 2 whereinsaid compressing means is operatively connected to said piercing meanswhereby movement of said diaphragm is resisted by the combined actuatingforce at said compressing means and said piercing means.
 4. The devicerecited in claim 3 wherein said compressing means is a bellows and isoperatively connected to said piercing means.
 5. The device recited inclaim 4 wherein said piercing means comprises a cutter and a biasedplunger located interjacent said bellows.
 6. The device recited in claim5 wherein said piercing means includes an adjusting means which isvented to ambient air pressure.
 7. The device recited in claim 2 whereinsaid venting ports comprise an internal venting port and an externalventing port wherein said interal port is in communication with saidfirst chamber whereby the internal air pressure impinges on saidcompressing means and said diaphragm, said external port opening ontosaid piercing means and said diaphragm and in communication with ambientair pressure.
 8. The device recited in claim 7 wherein said compressingmeans is operatively connected to said piercing means whereby saidinternal air pressure equals said ambient air pressure after saidpiercing means pierces said diaphragm.
 9. The device recited in claim 8wherein said compressing means is compressed independently of saidpiercing means.
 10. The device recited in claim 9 wherein saidcompressing means is a bellows and said piercing means comprises a4-blade cutter.